Lithium-Ion Exchange Membrane Water Electrolysis Using a Cationic Polymer-Modified Polyethersulfone Membrane

We previously reported lithium-ion exchange membrane water electrolysis using a commercial Nafion membrane for clean hydrogen production. In this study, a polyethersulfone (PES) membrane with high alkaline stability was dipped in a cationic aqueous solution to fabricate a PES-based membrane (c-PES membrane) as an alternative to Nafion. Compared with the commercial PES membrane, for the c-PES membrane, lithium ions can selectively transport from the anode to the cathode. Additionally, a high-porosity Ni-based porous transport layer (PTL) was used as an alternative to expensive Ti-PTL. Lithium-ion exchange membrane water electrolysis at 50 °C using c-PES membrane exhibited improved cell performance (1.13 A cm–2 @ 1.7 V) owing to lower ohmic and charge-transfer resistance, exhibiting the comparable performance to the reported water electrolysis systems. The carbonate formed during the process was effectively removed by injecting deionized water followed by H2SO4 solution, resulting in stable cell performance for 200 h.